how_to.md

In mcgregorian1/cgaR: A way to share common functions from CGA

How to add functions to this library

Adding functions to this package

This how-to comes from https://hilaryparker.com/2014/04/29/writing-an-r-package-from-scratch/. You can go through that yourself if you wish, or you can follow along here.

Example

Let's say you need a distraction. This is a real-world example.

First, it's helpful to be using the cgaR.Rproj. Otherwise, you need to setwd("./cgaR").

Create a new .R file containing only your new function and save in the "R" folder of this repo.

dawww <- function(choice=c("spring", "summer", "fall", "winter", "smolbabe", "doggo", "surprise")){

  # This is where all the pics are
  sites <- c('https://pixabay.com/photos/search/baby%20animals/',
             'https://pixabay.com/photos/search/spring/',
             'https://pixabay.com/photos/search/summer/',
             'https://pixabay.com/photos/search/fall/',
             'https://pixabay.com/photos/search/winter/',
             'https://pixabay.com/photos/search/puppies/',
             'https://pixabay.com/photos/search/flying/',
             'https://pixabay.com/photos/search/safari/',
             'https://pixabay.com/photos/search/mountain/')

  if(choice == "smolbabe"){
    pic <- html_session(sites[[1]])
  } else if(choice == "spring") {
    pic <- html_session(sites[[2]])
  } else if(choice == "summer") {
    pic <- html_session(sites[[3]])
  } else if(choice == "fall") {
    pic <- html_session(sites[[4]])
  } else if(choice == "winter") {
    pic <- html_session(sites[[5]])
  } else if(choice == "doggo"){
    pic <- html_session(sites[[6]])
  } else if(choice == "surprise") {
    pic <- html_session(sample(c(sites[[7]], sites[[8]], sites[[9]]), 1))
  }

  ##the language below is used for smolbabe but otherwise the functionality is the same

  # Play hide and seek with the bebbes
  hiddenbebbes <- html_nodes(pic, "img")

  # Found them!
  foundbebbes <- html_attr(hiddenbebbes,"src")
  foundbebbes <- foundbebbes[-grep("static", foundbebbes)]

  # Wait... We are missing some
  extrasneakybebbes <- html_attr(hiddenbebbes,"data-lazy-srcset")
  extrasneakybebbes <- str_split(na.omit(str_remove_all(extrasneakybebbes,"[1-9]x")),", ")
  extrasneakybebbes <- unlist(extrasneakybebbes)

  # Get em all together for a picture
  awww <- c(foundbebbes, extrasneakybebbes)

  # Take them home (ok maybe not all at once)
  temporary_file_location <- paste0(tempdir(), "/baby_animals.png")

  download.file(awww[sample(1:length(awww),1)],
                temporary_file_location, mode = "wb")

  # Bring the baby to R
  smolbabe <- load.image(temporary_file_location)

  # Display the smolbabe
  plot(smolbabe, yaxt = 'n', axes = FALSE)
}

Then add the documentation lines to the top like this. You don't need to save.

#' dawww
#'
#' Your daily dose of distraction. Make a choice, see the results, smile.
#'
#' This function is an extension of the original pupR package from https://github.com/melissanjohnson/pupR. All pictures are taken from pixabay.com.
#'
#' @param choice From the list above, you may only choose one.
#'
#' @return A photo of your choice is downloaded and displayed in the plot window.
#'
#' @importFrom rvest html_session html_nodes html_attr
#' @importFrom imager load.image
#' @importFrom stringr str_split str_remove_all
#'
#' @export
#' @examples
#' dawww("smolbabe") #get 1 picture of a smolbabe
#' replicate(5, "doggo") #get 5 pictures of doggos

*rest of function here*

Now in the console, run the following. This will automatically save and add the documentation to the package.

library(dev_tools)
library(roxygen2)
document()

That's it! To install the new version of the package, use install_github("mcgregorian1/cgaR").

If you're curious about what each of the "@" symbols refer to in the documentation, feel free to view the help for dawww to see what each one corresponds to. If you really want to get in it, you can read what Hadley has to say.

devtools::install_github("mcgregorian1/cgaR")
library(cgaR)
?dawww

mcgregorian1/cgaR documentation built on Dec. 8, 2019, 1:45 p.m.